Stimulus-Elicited Genomic Profile Markers of Alzheimer&#39;s Disease

ABSTRACT

The present invention relates to a method for diagnosing Alzheimer&#39;s Disease (AD) using PKC-elicited gene expression profiles PKC-activation elicits different genomic profiles in AD cells, as compared with control cells, which can he used to diagnose AD and individuals at risk for developing AD.

This application claims the benefit of U.S. provisional application Ser. No. 61/084,154, filed on Jul. 28, 2008, the disclosure of which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to a method for diagnosing Alzheimer's disease using PKC-elicited gene expression profiles.

BACKGROUND OF THE INVENTION

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the progressive decline of memory and cognitive functions. Dementia associated with AD is referred to as senile dementia of the Alzheimer's type (SDAT) in usage with Alzheimer's disease. AD is characterized clinically by progressive loss of memory, cognition, reasoning, judgment, and emotional stability that gradually leads to profound mental deterioration and ultimately, death. Although there are many hypotheses for the possible mechanisms of AD, one central theory is that the excessive formation and accumulation of toxic beta-amyloid (Aβ) peptides either directly or indirectly affects a variety of cellular events and leads to neuronal damage and cell death (Selkoe, Neuron. 1991; 6(4):487-98 1991; Selkoe, J Clin Invest. 2002; 110(10):1375-81).

AD is a progressive disorder with a mean duration of around 8-15 years between onset of clinical symptoms and death. AD is believed to represent the seventh most common medical cause of death and affects about 5 million people in the United States. The prevalence is expected to reach 7.7 million by 2030. About 1 in 8 people over the age of 65, 13% of this population, have AD (Alzheimer's Association 2008 Alzheimer's Disease Facts and Figures). AD currently affects about 15 million people world-wide (including all races and ethnic groups) and owing to the relative increase of elderly people in the population its prevalence is likely to increase over the next two to three decades. AD is at present incurable.

To date, there is limited opportunity for prophylactic intervention for AD because of insufficient diagnostic methods. At present, a definitive diagnosis of AD requires observing lesions in the brain tissue of patients post-mortem or, rarely, in small biopsied samples of brain tissue taken during an invasive neurosurgical procedure. Nevertheless, physicians routinely attempt to distinguish AD from other forms of dementia based on a battery of symptoms, relying on the known correlation between such symptoms and the lesions observed in biopsies. Tests currently used to diagnose AD include combinations of qualitative questionnaires such as the Mini-Mental State Examination (MMSE), the Mini-Cognitive Examination, and the AD Cooperative Study-Activities of Daily Living Scale (ADCS-ADL); physical and neurological evaluation; and structural (MRI, CT) and functional brain imaging (PET; FDG-PET). These tests are typically conducted to rule out other disease or conditions rather than to provide a definitive diagnosis of AD.

Some methods exist for detecting pathogenic biomarkers for AD, such as Aβ, Tau, and Neural thread protein/AD7C in living subjects. For example, detection of Aβ in a living subject include direct (imaging) or indirect (biochemical) detection. In vivo imaging of Aβ can be achieved using radioiodinated flavone derivatives as imaging agents (Ono et al., J Med Chem. 2005; 48(23):7253-60) and with amyloid binding dyes such as putrescein conjugated to a 40-residue radioiodinated A peptide (yielding ¹²⁵I-PUT-A 1-40). This agent was shown to cross the blood-brain barrier and bind to Aβ plaques (Wengenack et al., Nature Biotechnology. 2000; 18(8): 868-72). Imaging of Aβ also was shown using stilbene [¹¹C]SB-13 and the benzothiazole [¹¹C]6-OH-BTA-1 (also known as [¹¹C]PIB) (Nicholaas et al., Am J Geriatr Psychiatry. 2004; 12:584-595).

Quantitation of Aβ (1-40) in the peripheral blood also has been demonstrated using high-performance liquid chromatography coupled with tandem mass spectrometry in a linear ion trap (Du et al., J Biomol Tech. 2005; 16(4):356-63). Detection of single Aβ protein aggregates in the cerebrospinal fluid of Alzheimer's patients by fluorescence correlation spectroscopy also has been described (Pitschke et al., Nature Medicine. 1998; 4: 832-834). U.S. Pat. No. 5,593,846 describes a method for detecting soluble Aβ. Indirect detection of Aβ peptide and receptor for advanced glycation end products (RAGE) using antibodies also has been described. Lastly, biochemical detection of increased BACE-1 activity in cerebrospinal fluid using chromogenic substrates also has been postulated as diagnostic or prognostic indicator of AD (Verheijen et al., Clin Chem. 2006; 52:1168-1174). Other methods include detection of Tau, and Neural thread protein/AD7C in the cerebrospinal fluid.

In an attempt to improve treatment and diagnosis of AD, numerous gene-expression profiles have been generated to compare genes expressed in post-mortem brain tissue with those expressed normal brain tissue using various techniques including microarray laser capture microdissection (Loring et al., DNA and Cell Biology. 2001; 20(11): 683-95; Mufson et al., Neurochem. Res. 2003; 27(10): 1035-48; Dunckley et al., Neurobiol Aging. Oct. 1, 2005; Brooks et al., Brain Res. 2007; 1127(1):127-35; Liang et al., Physiological Genomics. 2008; 33:240-256; Liang et al., Proc Natl Acad Sci USA. Mar. 10, 2008); Some gene-expression profiles using peripheral tissues, such as lymphocytes or fibroblasts, also have been generated in an attempt to identify gene expression profiles associated with familial (inherited) AD or evaluate the effect of a potential treatment on differentially expressed genes (Nagasaka et al., Proc. Natl. Acad. Sci. USA . 2005; 102(41): 14854-14859).

Current diagnostic measures for AD include identification of a clinical core of early, progressive and significant episodic memory loss plus one or more abnormal biomarkers (biological indicators) characteristic of AD, including atrophy (wasting) of the temporal lobe as shown on MRI; abnormal Aβ protein concentrations in the cerebrospinal fluid; a specific pattern showing reduced glucose metabolism on PET scans of the brain; and a genetic mutation associated with within the immediate family.

Like the physical and mental examinations, the foregoing methods are not yet totally reliable or accurate for a diagnosis of Alzheimer's because the same gene patterns are found in other diseases or conditions. As a result, the costs of diagnosing AD are enormous because of the numerous tests and specialists involved and because the inability to diagnose Alzheimer's in early stages precludes patients and their families from adequately planning for the future, increasing costs for long-term care. In addition, estimates rates of misdiagnoses or no definitive diagnosis are in the range of 50-75%.

There remains a need for a simpler way to achieve more definitive diagnoses of AD that are less expensive and invasive, more accurate, and which can be used at an earlier stage for quicker intervention. Importantly, because the neurodegenerative process and substantial cell loss likely begins well before manifestation of the cognitive symptoms of AD, an effective diagnostic test that could more accurately diagnose AD, including early AD and even a pre-disposition to AD, would be invaluable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. FIG. 1 depicts the decreased expression of certain genes in PKC-activated AD cells compared with PKC-activated control cells according to the method of the present invention.

FIG. 2. FIG. 2 depicts the increased expression of certain genes in PKC-activated AD cells compared with PKC-activated control cells according to the method of the present invention.

DETAILED DESCRIPTION

The invention provides methods for diagnosing Alzheimer's disease (AD). These methods are based upon detecting changes in gene expression following activation of protein kinase C (PKC). Protein kinase C (PKC) is one of the largest gene families of protein kinase (Liu and Heckman, Cell Signal. 1998; 10:529-542). Several PKC isozymes are expressed in the brain, including PKC, PKCβ1, PKCβ2, PKCδ, PKCε, and PKCγ. PKC is primarily a cytosolic protein, but with stimulation it translocates to the membrane. PKC has been shown to be involved in numerous biochemical processes relevant to Alzheimer's disease. Deficits of PKC isoforms have been found in AD brain tissue and in fibroblasts from AD patients. PKC also activates TNF-alpha converting enzyme (TACE), which is an enzyme that is involved in the proteolytic conversion of membrane-bound amyloid precursor protein (APP) to its non-pathogenic soluble form, known as soluble APP-alpha or sAPPalpha (Alkon et al., Trends in Pharmacological Sciences. 2007; 28(2): 51-60; Hurtado et al., Neuropharmacology. 2001; 40(8): 1094-1102). These sAPPα-producing enzymes are referred to generically as alpha-secretases. Activation of TACE by PKC also reduces cellular levels of pathogenic Aβ, which is produced by cleavage of APP by the beta-secretase enzyme (BACE). This is likely due to the fact that the TACE cleavage site is within the Aβ domain of APP. Overexpression of PKCε has been shown to selectively increased the activity of endothelin-converting enzyme, which degrades Aβ (Choi et al., Proc. Natl. Acad. Sci. USA. 2006; 103(21): 8215-8220). Moreover, studies have demonstrated that one PKC activator, bryostatin-1, reduces the levels of soluble Aβ and enhances recent memory (Etcheberrigaray et al., Proc Natl Acad Sci USA. 2004; 101(30):11141-6; U.S. Pat. No. 6,825,229).

In addition, other studies have demonstrated that the translocated PKC can phosphorylate glutamate receptors, including NMDA receptors, as well as other proteins that are located in the postsynaptic density (Suzuki et al., Brain Res. 1993; 619:69-75). PKC has several impacts on NMDA receptors (MacDonald et al., Curr Drug Targets. 2001; 2:299-312). Specifically, PKC enhances the surface expression of NMDA receptors (Xiong et al., Mol Pharmacol. 1998; 54:1055-1063; Lan et al., Nat Neurosci. 2001; 4:382-390). Calcium flux through NMDA receptors is thought to play a critical role in synaptic plasticity, a cellular mechanism for learning and memory. One of the drugs approved to treat AD, memantine, binds to the NMDA receptor and inhibit the prolonged influx of calcium ions which forms the basis of neuronal excitotoxicity in AD.

Because the various PKC isozymes are involved in AD, the detection of Alzheimer's disease-specific differences in PKC-elicited gene expression and function in peripheral tissues provides the basis for highly practical and efficient tests for the early diagnosis of Alzheimer's disease, and provide a basis for identifying targets for therapeutic drug development.

Definitions

Protein Kinase C refers to any isoforms of PKC encoded by a PKC gene. The PKC gene family consists presently of 11 genes which are divided into four subgrounds: 1) classical PKCα (alpha), β1, β2 (beta) (β1 and β2 are alternatively spliced forms of the same gene) and γ (gamma), 2) novel PKCδ (delta), ε (epsilon), η (eta) and 0 (theta), 3) atypical PKCξ (zeta), λ (lambda), η (eta) and ι (iota) and 4) PKCμ (mu). The α, β1, β2, and γ isoforms are calcium ion dependent, phospholipid and diacylglycerol-dependent and represent the classical isoforms of PKC, whereas the other isoforms are activated by phospholipid and diacylglycerol but are not dependent on calcium. All isoforms encompass 5 variable (V1-V5) regions, and the α, β1, β2, and γ isoforms contain four (C1-C4) structural domains which are highly conserved. All isoforms except PKC α, β1, β2, and γ lack the C2 domain, and the λ, η isoforms also lack nine of two cysteine-rich zinc finger domains in C1 to which diacylglycerol binds. The C1 domain also contains the pseudosubstrate sequence which is highly conserved among all isoforms, and which serves an autoregulatory function by blocking the substrate-binding site to produce an inactive conformation of the enzyme (House et al., Science. 1997; 238:1726-1728).

The term “Alzheimer's Disease” or “AD” refers to any condition where Aβ and/or neurofibrillary tangles eventually accumulates in the cells of the central nervous system, which accumulation that cannot be attributed to other disease or conditions such as CAA. AD may be heritable in a Familial manifestation, or may be sporadic. As used herein, AD includes Familial, Sporadic, as well as intermediates and subgroups thereof based on phenotypic manifestations. In addition, this term includes the development of Aβ in subjects having Down's Syndrome.

The term “Sporadic AD” refers to AD that develops later in life, usually after the age of about 65, and is not associated with a family history of AD or a mutation in a gene identified as being a risk factor for AD.

The term young-onset refers to AD that occurs in a person under age about 65. Young-onset includes but is not limited to Familial AD.

Familial AD refers to AD associated with inherited mutations in the presenilin-1 gene (PSEN-1), presenilin-2 gene (PSEN-2); the gene encoding Amyloid beta precursor protein (APP), and/or the gene encoding apolipoprotein E (APOE).

Early-stage AD refers to the stage of AD associated with moderate symptoms of cognitive decline such as memory loss or confusion. Memory loss or other cognitive deficits are noticeable, yet the person can compensate for them and continue to function independently. This stage correlates with Stage 4 of the Functional Assessment Staging (FAST) scale or mild AD according to the criteria defined in the Diagnostic and Statistical Manual of Mental disorders, 4th Edition (DSM-IV-TR) (published by the American Psychiatric Association), NINCDS-ADRDA, or MMSE.

Mild Cognitive Impairment (MCI) refers to a transition stage between the cognitive changes of normal aging and AD. A subject with MCI has cognitive impairments beyond that expected for their age and education, but that do not interfere significantly with their daily activities. A person with MCI may have impairments with memory, language, or another mental function. Not all subjects with MCI develop AD. As used herein, a subject with MCI is considered at risk for developing AD.

Other risk factors for AD are advancing age, mutations in PSEN-1, PSEN-2, APP and APOE, and

As used herein, the term “subject” means a mammal. In one embodiment, the subject is a human.

The term “normal subject,” as used herein, is relative to AD. That is, the subject does not exhibit AD, is not diagnosed with the specified disease, and is not at risk for developing the disease.

“Peripheral tissue” refers to a tissue that is not derived from neuroectoderm, and specifically includes olfactory epithelium, tongue, skin (including dermis and/or epidermis), and mucosal layers of the body.

The term “differentially expressed” or “differential expression” as used herein refers to a measurement of a cellular constituent varies in two samples, a control sample and a test sample. The cellular constituent can be either upregulated in the experiment relative to the control or downregulated in the experiment relative to the control sample.

As used herein, the phrase “detecting the level of expression” includes methods that quantitate expression levels as well as methods that determine whether a gene of interest is expressed at all. The detection can be qualitative or quantitative. In one specific embodiment, the differential expression is statistically significant

As used herein, “upregulating” or “upregulation” means detecting an increased the amount or activity of a gene or gene product relative to a baseline or control state, through any mechanism including, but not limited to increased transcription, translation and/or increased stability of the transcript or protein product. Increased expression in a test cell includes a situation where the corresponding gene in a control cell is either unchanged by PKC activation or is downregulated in response to PKC activation.

As used herein, “down regulating” or “downregulation” refers to detecting a decrease in the amount or activity of a gene or gene product relative to a baseline or control state, through any mechanism including, but not limited to decreased transcription, translation and/or decreased stability of the transcript or protein product. Decreased expression in a test cell includes a situation where the corresponding gene in a control cell is either unchanged by PKC activation or is upregulated in response to PKC activation.

A “change in gene expression” refers to detection of upregulation or downregulation.

The term “microarray” or “nucleic acid microarray” refers to a substrate-bound collection of plural nucleic acids, hybridization to each of the plurality of bound nucleic acids being separately detectable. The substrate can be solid or porous, planar or non-planar, unitary or distributed. Microarrays or nucleic acid microarrays include all the devices so called in Schena (ed.), DNA Microarrays: A Practical Approach (Practical Approach Series), Oxford University Press (1999); Nature Genet. 21(1)(suppl.)1-60 (1999); Schena (ed.), Microarray Biochip: Tools and Technology, Eaton Publishing Company/BioTechniques Books Division (2000). These microarrays include substrate-bound collections of plural nucleic acids in which the plurality of nucleic acids are disposed on a plurality of beads, rather than on a unitary planar substrate, as is described, inter alia, in Brenner et al., Proc. Natl. Acad. Sci. USA 2000; 97(4):1665-1670.

The terms “about” and “approximately” shall generally mean an acceptable degree of error for the quantity measured given the nature or precision of the measurements. Typical, exemplary degrees of error are within 20 percent (%), preferably within 10%, and more preferably within 5% of a given value or range of values. Alternatively, and particularly in biological systems, the terms “about” and “approximately” may mean values that are within an order of magnitude, preferably within 5-fold and more preferably within 2-fold of a given value. Numerical quantities given herein are approximate unless stated otherwise, meaning that the term “about” or “approximately” can be inferred when not expressly stated.

DESCRIPTION OF EMBODIMENTS

In one embodiment, the invention provides a method of diagnosing AD by detecting differences in the expression levels of genes in cells from a subject suspected of developing or having AD, in response to stimulation with a PKC activator (“test cells”), compared to expression of the same genes in normal control cells (“control cells”) following stimulation with a PKC activator. In a specific embodiment, the control cells are derived age-matched control subjects and are stimulated with the same PKC activator as the test cells.

In another embodiment of the invention, increased gene expression in PKC-stimulated test cells compared to PKC-stimulated control cells (upregulation) indicates the presence of AD. In another aspect, decreased gene expression in stimulated test cells compared to PKC-stimulated control cells (downregulation) indicates the presence of AD. In a third aspect, absence of increased gene expression in stimulated test cells compared to PKC-stimulated control cells indicates the presence of AD. In a fourth aspect, absence of decreased expression in stimulated test cells compared to PKC-stimulated control cells indicates the presence of AD.

In another specific embodiment, the present invention provides a method for diagnosing early-stage AD by detecting the differential changes in gene expression. In specific embodiments, the method of the invention can be used to distinguish Alzheimer's pathology or dementia from that associated with other forms of dementia, such as frontotemporal degenerative dementias (e.g., Pick's disease, corticobasal ganglionic degenerations, and frontotemporal dementia), Huntington's disease, Creutzfeldt Jakob disease, Parkinson's disease, cerebrovascular disease, head trauma, and substance abuse.

In a further embodiment, the invention provides a method of evaluating disease progression by applying the methods to two or more samples from the same patient taken on separate occasions. This embodiment can also be used to evaluate the effect of any AD treatment administered after the first sample is taken but before the send sample is taken. Exemplary AD treatments that can be evaluated include Namenda® (memantine), Aricept® (donapazil) and Razadyne® (galantamine), an Exelon® (rivastigmine).

The present invention further provides a method of screening therapeutic substances for the treatment or prevention of AD by evaluating the effects of a test agent on the differential expression of genes according to the methods described herein.

In another embodiment, the present invention provides kits to carry out the diagnostic method of the present invention.

Table 1 provides the GenBank accession number for the genes identified to be down-regulated in the AD cells compared with the control cells. Table 2 provides the GenBank accession number for the genes identified to be upregulated in the AD cells compared with the control cells. Table 3 provides the specific genes and their relationship(s), and molecular biological and cellular functions.

In specific embodiments, the diagnostic method of the present invention comprises detecting differential expression in the control sample and the test sample of at least two genes listed in Table 1 or Table 2 in Example 1, below. In another specific embodiment, the diagnostic method of the present invention comprises detecting differential expression in the control sample and the test sample of at least five genes listed in Table 1 or Table 2. In a further specific embodiment, the diagnostic method of the present invention comprises detecting differential expression in the control sample and the test sample of at least ten genes listed in Table 1 or Table 2. In yet a further specific embodiment, the diagnostic method of the present invention comprises detecting differential expression in the control sample and the test sample of at least fifteen genes listed in Table 1 or Table 2. The specific genes and their relationship(s), molecular biological and cellular functions are described in Table 3.

Biological Samples

The present invention provides methods for the diagnosis of Alzheimer's disease using cells from subjects suspected of being at risk for developing AD or suspected of having AD. In the methods of the invention, the cells that are taken from the subject include any viable cells. In one embodiment, the cells are from peripheral tissues, i.e., non-neural tissue. In further specific embodiments, the tissue is skin, blood, mucosa, or cerebrospinal fluid.

In another specific embodiment, the cells are fibroblasts, epithethial cells, endothelial cells, or hematopoietic cells including lymphocytes. In a further specific embodiment, the cells are skin epithelial cells, skin fibroblast cells, blood cells or buccal mucosa cells. The cells may be fresh, cultured, or frozen prior to analysis. In a specific embodiment, a punch skin biopsy can be used to obtain skin fibroblasts from a subject. These fibroblasts are analyzed directly or introduced into cell culture conditions. In another specific embodiment, the cells are isolated from excised using laser capture microdissection to obtain a homogenous population of cells of the same type.

PKC Activators

The method of the present invention contemplates using any compound known to have the ability to activate PKC. PKC activators are known in the art and include bradykinin, phorbol esters such as phorbol 12-myristate 13-acetate (PMA), phorbol 12,13-dibutyrate (PDBu), phorbol 12,13-didecanoate (PDD), bombesin, cholecystokinin, thrombin, prostaglandin F2α and vasopressin. Other PKC activators include natural and unnatural diacylglycerols (DAG), including diacylglycerols with various fatty acids in the 1,2-sn configuration are active. In a specific embodiment, the DAG contains an unsaturated fatty acid. In one embodiment, the PKC activator is a macrocyclic lactone, including but not limited to those in bryostatin compound class and neristatin compound class. In another embodiment, the PKC activator is a benzolactam. In a further embodiment, the PKC activator is a pyrrolidinone. In a specific embodiment, the macrocyclic lactone is bryostatin. In a more specific embodiment, the bryostatin is bryostatin-1, -2, -3, -4, -5, -6, -7, -8, -9, -10, -11, -12, -13, -14, -15, -16, -17, or- 18.

The present invention also contemplates diagnoses of AD by detecting changes in gene expression in cells contacted with PKC activators selective for a specific isoform or isoforms of PKC. For example, benzolactam activates PKC α, β and γ. Bryostatin-1 selectively activates PKCα. Bradykinin activates PKCα, -δ, and -ζ. PKCε and η have been showed to be activated upon the administration of nitric oxide donors such as diethylenetriamine/NO (DETA/NO) and S-nitroso-N-acetylpenicillamine (SNAP) diethylenetriamine/NO (DETA/NO) and S-nitroso-N acetylpenicillamine (SNAP) (Balafanova et al., J. Biol. Chem. 2002; 277(17): 15021-15027). More recently, polyunsaturated fatty acid derivatives have been shown to selectively activate PKCε.

Exemplary concentrations of PKC activators that can be used to stimulate cells according to the methods of the present invention at a range of about 0.01 nM to 100 μM, preferably, 0.5 nM to 10 μM, more preferably 1 nM to 1 μM, and most preferably 10 nM to 500 nM.

Gene Expression Profiling

Methods of evaluating changes in gene expression are well known in the art. The present invention contemplates both low-throughput methods such as Northern Blotting, in situ hybridization, and reverse transcription quantitative polymerase chain reaction (RVQ-PCR), and high-throughput methods such as microarrays and SAGE to detect differential gene expression. Preferably, detection is conducted using automatic, computerized equipment in a high-throughput setting, such as microarray technology. Such high-throughput equipment are commercially available, and techniques are well-known in the art.

In one specific embodiment, the method of the present invention provides detecting the gene transcript such as mRNA, including microRNA, cDNA or cRNA. The transcript can be from both coding and non-coding regions of the gene. The transcript can be detected in situ in the cell or in purified form extracted from the cell. In a specific embodiment, the nucleic acid is isolated and purified from the cell and then used in the gene expression assay.

In another embodiment, the method of the present invention provides detecting the protein product, or portion thereof, expressed from a gene transcript. Protein-based assays are also well-known in the art and include low-throughput methods such as Western blotting and ELISA, and high throughput protein microarrays.

In a further embodiment, the method of the present invention further comprises detecting the activity or activation state of the detected protein product, such as the phosphorylation of given protein.

In a specific embodiment of the invention, gene transcripts (e.g., cDNAs) from two different cells are hybridized to the binding sites of known gene transcripts on a microarray, one which is the test cell that has been stimulated with PKC activator and another the control cell, preferably of the same cell type, which has been stimulated with a PKC activator, preferably the same PKC activator. The nucleic acid derived from each of the two cell types are differently labeled so that they can be distinguished. Use of microarrays to evaluate differentially expressed transcripts are well known. See, e.g., U.S. Pat. No. 6,973,388. This technique typically involves preparing or purchasing microarrays containing known cDNA transcripts, extracting and labeling RNA from test cells, hybridizing the test RNA to the array, detecting and visualizing signal, performing statistical analysis on the results, and, optionally, validating the microarray results using low-throughput techniques.

Pre-made cDNA microarrays are commercially available from e.g., Affymetrix® (Santa Clara, Calif.), Agilent Technologies® (Santa Clara, Calif.) and AlphaGene® (Woburn, Mass.). These include whole genome arrays and targeted subsets of known genes.

In another specific embodiment, differential expression of genes is detected using serial analysis of gene expression (SAGE). SAGE quantitatively determines the amount of times a small portion of a specific mRNA transcript is expressed (a tag). The output of SAGE is a list of short sequence tags and the number of times it is observed. The major difference between microarray hybridization and serial analysis of gene expression (SAGE) techniques is that the latter does not require prior knowledge of the sequences to be analyzed; SAGE is a sequencing-based gene expression profiling technique.

In one embodiment of the invention, the test cells will demonstrate an observable difference in the level of expression of one or more genes compared with the level of expression of the same gene or genes in the control cells. In a specific embodiment, the differential expression is quantitative. In a further embodiment, the level gene expression detected in the test cells is about 1-fold, 2-fold, 5-fold, 10-fold and 100-fold upregulated or downregulated compared to the control cells.

Screening Methods for Therapeutics

In yet a further aspect, this invention relates to methods of screening therapeutic substances for the treatment or prevention of AD using the diagnostic tests described herein. According to this embodiment, compounds which reverse or improve the observed differences in gene expression described herein (i.e. back to or toward levels found in PKC-activated control cells) would be identified and selected as a substance potentially useful for the treatment or prevention of AD.

In one embodiment, the screening method comprises the steps of contacting cells from a subject that has been diagnosed with AD with a test compound for a period of time, followed by contacting the cells with an agent that is a PKC activator, and determining whether the test compound alters the differential expression of the genes identified according to the methods of the present invention towards levels observed in control cells from normal subjects.

In a specific embodiment, the cells contacted with the test compound are derived from a subject diagnosed with AD according to the methods of the present invention.

Kits

This invention also relates to kits comprising products useful for carrying out the diagnostic methods of the invention. The kits may also include instruments, buffers and storage containers necessary to perform one or more biopsies, such as punch skin biopsies. The kits can include high-density oligonucleotide arrays, reagents for use with the arrays, signal detection and array-processing instruments, gene expression databases and analysis and database management software. The kits may also contain instructions relating to the identification of differentially expressed genes used for the AD diagnosis.

As stated previously, the kits may contain a single diagnostic test or any combination of the tests described herein. All of the differences disclosed herein between control and AD cells form the basis for the clinical tests and diagnostic kits for AD disease diagnosis, as well as the methods of screening compounds for treatment or prevention of AD disclosed herein.

Combination Diagnostic Methods

It is contemplated that the diagnostic methods of the present invention may be used in combination with any other diagnostic methods. Exemplary methods include physical and neurological evaluation; biomarker detection; and structural (MRI, CT) and functional brain imaging (PET; FDG-PET).

As one example, the methods of the present invention can be used in combination with evaluating mutations in the genes known to be involved in Familial AD. Additional methods of diagnosing AD are described in U.S. Pat. Nos. 6,080,582 and 6,300,085 to Alkon et al., which methods detect the absence of potassium ion channels in the cells of an AD patient, differences in intracellular calcium ion concentration in AD and non-AD cells in response to potassium channel blockers specific for the potassium ion channel that is absent in the cells of an AD patient, and differences between AD and non-AD cells in response to activators of intracellular calcium release such as activators of inositol-1,4,5-trisphosphate (IP3). Additional diagnostic methods are described in application publication number WO2007/047029 to Alkon et al. directed to diagnosing AD in a subject by detecting alterations in the ratio of specific phosphorylated MAP kinase proteins (Erk1/Erk 2) in cells after stimulation with a PKC activator. See also, Zhao et al., Neurobiol Dis. October 2002; 11(1):166-83.

EXAMPLES Example 1 Determination of Differentially-Expressed Genes in PKC-Activated AD Cells

This example describes the identification of differentially-expressed genes in AD cells according to the method of the present invention.

Materials and Methods

Bradykinin (BK; molecular weight, 1,060.2) was purchased from Calbiochem (San Diego, Calif.).

Skin Fibroblast Cell Culture. Human skin fibroblast cell culture systems were used for these studies. Banked skin fibroblasts cells with the diagnoses AD and age-matched control from the Coriell Institute of Medical Research were cultured (supplemented with 10% serum and penicillin/streptomycin) at 37° C. with 5% CO₂ to the 90-100% confluence stage in 25-ml cell culture flasks. Cells were “starved” in serum-free medium (DMEM) for 24 h. A solution of 10 nM BK (in DMSO) was prepared in DMEM with 10% serum. Seven milliliters of the 10 nM BK solution was added to the culture flasks and incubated at 37° C. for 10 min. For the controls, the same amount of DMSO was added in DMEM with 10% serum. Seven milliliters of this medium with DMSO (<0.01%) was added to the culture flasks and incubated at 37° C. for 10 min. After washing four times with cold (4° C.) 1×PBS, flasks were kept in a dry ice/ethanol mixture for 15 min. Flasks were then removed from the dry ice/ethanol mixture, and the cells were treated with trypsin-EDTA (Invitrogen), centrifuged 400×g for 5 min, and the pellets were washed twice in PBS. The pellets were then quickly frozen in ethanol-CO₂ ice and transferred to −70° C.

Total RNA was then isolated from the cultured fibroblast pellets using an RNeasy mini kit (Qiagen, Hilden, Germany) according to the manufacturer's protocol, which typically a yield of 5-10 μg of RNA per 10⁶ cells. Nucleic acid was extracted from the cells according to standard procedures.

Microarray Analysis. For microarray probing, reverse transcription, second-strand synthesis, and probe generation were performed according to the GeneChip Expression Analysis Technical Manual (Affymetrix, Santa Clara, Calif.). The generated probe was subjected to hybridization to oligonucleotide DNA chips, Human Genome U133A (Affymetrix). The arrays were scanned with a GeneArray Scanner (Hewlett-Packard). Image Analysis and Data Quality Control. Scanner output image files were normalized and filtered by using MICROARRAY SUITE 5.0 software (Affymetrix). Normalization was performed by global scaling, with the arrays scaled to an arbitrary signal intensity value of 100. The detection metric (Presence or Absence calls) and decision of significant gene expression for a particular gene (probe set) was determined by using default parameters in the MICROARRAY SUITE 5.0 software.

Table 1 shows the genes down-regulated in AD cell lines following bradykinin stimulation but either activated or unchanged following bradykinin stimulation in age matched controls. Table 2 shows the genes up-regulated in AD cell lines following bradykinin stimulation but either down-regulated or unchanged following bradykinin stimulation in age matched controls. Table 3 provides the specific genes and their relationship(s), and molecular biological and cellular functions.

TABLE 1 Genes Down-regulated in AD GenBank % Gene encoding Accession No. CHANGE Homo sapiens adaptor protein with pleckstrin homology and src NM_020979.1/DEF 99 homology 2 domains (APS), mRNA Homo sapiens , KIAA1080 protein; Golgi-associated, gamma-adaptin BC000284.1/DEF 64 ear containing, ARF-binding protein 2, clone MGC: 1002, mRNA, Homo sapiens sodium channel, voltage-gated, type I, beta polypeptide NM_001037.1/DEF 51 (SCN1B), mRNA. Homo sapiens phosphoserine phosphatase-like (PSPHL), mRNA. NM_003832.1/DEF 77 Homo sapiens hypothetical protein FLJ12455 (FLJ12455), mRNA. NM_022078.1/DEF 73 Hs.50283 ESTs, Weakly similar to DUS8_HUMAN DUAL AI492892 74 SPECIFICITY PROTEIN PHOSPHATASE 8 H. sapiens Hs.112451 ESTs T86629 76 Hs.72325 Human DNA sequence from clone RP1-187J11 on AW418666 79 chromosome 6q11.1-22.33. Contains the gene for a novel protein similar to S. pombe and S. cerevisiae predicted proteins, the gene for a novel protein similar to protein kinase C inhibitors, the 3 end of the gen Hs.104613 RP42 homolog AW468880 69 Homo sapiens protein kinase, AMP-activated, beta 2 non-catalytic NM_005399.1/DEF 72 subunit (PRKAB2), mRNA. Hs.294141 ESTs, Weakly similar to alternatively spliced product using BF433071 75 exon 13A H. sapiens Homo sapiens similar to CG9578 gene product (MGC3794), mRNA NM_152902.1 61 Hs.1742 IQ motif containing GTPase activating protein 1 AI679073 88 Homo sapiens paired mesoderm homeo box 1 (PMX1), transcript NM_006902.2/DEF 66 variant pmx-1a, mRNA. Hs.20237 DKFZP566C134 protein BF000166 85 Homo sapiens ATPase, Ca++ transporting, plasma membrane 4 NM_001684.1/DEF = 87 (ATP2B4), mRNA. Hs.127478 ESTs, Weakly similar to T32252 hypothetical protein AI813654 79 T15B7.2 Hs.50283 ESTs, Weakly similar to DUS8_HUMAN DUAL AI492892 74 SPECIFICITY PROTEIN PHOSPHATASE 8 H. sapiens

TABLE 2 Genes Up-regulated in AD GeneBank % Gene Encoding Accession No. CHANGE Hs.69559 K1AA1096 protein AW238632 46 Hs.283732 ESTs AW611729 97 Hs.103189 lipopolysaccharide specific response-68 protein AV740879 154 Hs.6019 Homo sapiens cDNA: FLJ21288 fis, clone COL01927 AA639752 475 Homo sapiens full length insert cDNA clone AP088033 74 Hs.9977 ESTs AW182938 155 Hs.214646 KIAA0447 gene product AL031282 150 Hs.78893 KIAA0244 protein BF430956 61 Hs.42699 ESTs AW956580 56 Hs.3640 Homo sapiens mRNA AI394529 60 Hs.30957 Homo sapiens mRNA; cDNA DKFZp434E0626 AL137364.1 86 Homo sapiens forkhead box F2 (FOXF2), mRNA. NM_001452.1 97 K1AA1483 protein BF111616 84 Hs.28959 ESTs AI457436 80 Homo sapiens clone FBD3 Cri-du-chat critical region mRNA AF056433 52 Homo sapiens nuclear autoantigen (GS2NA), mRNA. / NM_014574.1 71 Homo sapiens Ste-20 related kinase (SPAK), mRNA. NM_013233.1 46 Hs.250646 baculoviral IAP AI017106 285 Hs.181300 sel-1 (suppressor of lin-12, C. elegans)-like AI927770 75 Hs.5151 RAN binding protein 7 BG291787 74 EST SWlSNF related, matrix associated, actin dependent regulator of AI760760 56 chromatin, subfamily a, member 3 Homo sapiens eukaryotic translation initiation factor 4 gamma, 3 NM_003760.2/DEF 68 (EIF4G3), mRNA. Homo sapiens chromosome condensation protein G (HCAP-G), NM_022346.1/DEF 174 mRNA. Hs.293690 ESTs AI816281 62 Homo sapiens RBP1-like protein (BCAA), mRNA. NM_016374.2/DEF 68 Hs.265644 ESTs AW963328 74 Hs.8895 ESTs AA147933 63 Homo sapiens , Similar to RIKEN cDNA 1700073K01 gene, clone BC005357.1 63 MGC: 12458, mRNA Hs.144477 hypothetical protein PRO2975/FL = gb: AF119911.1 BG534245 55 Homo sapiens mRNA for TGF-betaIIR alpha, complete cds. D50683.1/DEF 55 Homo sapiens cDNA FLJ33255 fis, clone ASTRO2005553. BU689502 105 Homo sapiens ubiquitin specific protease 8 (USP8), mRNA. NM_005154.1/DEF 79 Hs.79353 hypothetical protein FLJ13576 (TFDP1) R60866 66 Hs.79828 hypothetical protein FLJ20333 A1823905 81 Homo sapiens hypothetical protein FLJ10461 (FLJ10461), mRNA. NM_018098.1/DEF 45

TABLE 3 Specific subsets of genes and their biological, molecular and cellular functions. Gene Bank Gene ID/Gene Biological Cellular Title symbol processes Molecular functions components Pathway Transforming D50683.1/ protein amino nucleotide binding membrane TGF_Beta_Signaling_Pathway growth factor, DEF acid beta receptor II TGFBR2 phosphorylation (70/80 kDa) transmembrane magnesium ion integral to receptor protein binding membrane serine/threonine kinase signaling pathway Positive protein kinase activity integral to regulation of membrane cell proliferation protein Receptor serine/threonine kinase complex activity mransmembrane receptor protein serine/threonine kinase activity Receptor signaling protein serine/threonine kinase activity Receptor activity Transforming growth factor beta receptor activity Transforming growth factor beta receptor activity, type II Protein binding ATP binding Kinase activity Transferase activity Manganese ion binding metal ion binding ATPase, Ca++ NM_001684.1/ transport nucleotide binding plasma transporting, DEF membrane plasma ATP2B4 transport magnesium ion plasma membrane 4 binding membrane ion transport catalytic activity plasma membrane cation transport calcium-transporting integral to ATPase activity plasma membrane calcium ion calcium-transporting membrane transport ATPase activity metabolic calcium ion binding integral to process membrane protein binding calmodulin binding ATP binding calcium ion transmembrane transporter activity ATPase activity, coupled to transmembrane movement of ions, phosphorylative mechanism hydrolase activity hydrolase activity, acting on acid anhydrides, catalyzing transmembrane movement of substances metal ion binding phosphoserine NM_003832.1/ L-serine magnesium ion phosphatase DEF metabolic binding PSPH process L-serine catalytic activity biosynthetic process metabolic phosphoserine process phosphatase activity cell proliferation phosphoserine phosphatase activity amino acid protein binding biosynthetic process hydrolase activity phosphoric monoester hydrolase activity eukaryotic NM_003760.2/ translation RNA cap binding eukaryotic Translation_Factors translation DEF regulation of RNA binding translation initiation factor EIF4G3 translation initiation factor 4 gamma, 3 regulation of translation initiation 4F complex translational factor activity initiation regulation of binding translational initiation RNA metabolic protein binding process protein binding translation factor activity, nucleic acid binding epithelial cell NM_018098.1/ intracellular signal transducer intracellular transforming DEF signaling activity sequence 2 ECT2 cascade oncogene regulation of guanyl-nucleotide Rho protein exchange factor signal activity transduction positive Rho guanyl-nucleotide regulation of I- exchange factor kappaB activity kinase/NF- kappaB cascade protein binding BAT2 domain AW238632 containing I BAT2DI helicase-like AI760760 transcription nucleotide binding nucleus transcription EST regulation of nucleic acid binding nucleus factor HLTF transcription, DNA-dependent regulation of DNA binding transcription from RNA polymerase I1 promoter chromatin DNA binding modification RNA polymerase II transcription factor activity heIicase activity protein binding ATP binding zinc ion binding transcription activator activity hydrolase activity ATPase activity metal ion binding chromosome AV740879 transcription DNA binding nucleus 14 open C14orf43 regulation of reading frame transcription, 43 DNA-dependent similar to AL031282 membrane solute carrier RP11- integral to family 35, 345P4.4 membrane member E2 paired related NM_006902.2/ regulation of DNA binding nucleus homeobox 1 DEF transcription, PRRXI DNA-dependent multicellular transcription factor organismal activity development regulation of transcription transcription coactivator activity sequence-specific DNA binding AT rich NM_0I6374.2/ chromatin nucleic acid binding chromatin interactive DEF assembly or domain 4B ARID4B disassembly (RBP I-like) transcription DNA binding intracellular regulation of chromatin binding nucleus transcription, DNA-dependent cytoplasm transcription TFDP1 S phase of DNA binding nucleus Cell_cycle_KEGG factor Dp-1 R60866 mitotic cell cycle transcription transcription factor transcription G1_to_S_cell_cycle_Reactome activity factor complex regulation of transcription factor transcription, activity DNA-dependent regulation of transcription transcription coactivator activity from RNA polymerase II promoter apoptosis protein binding cell cycle transcription activator activity cell proliferation epidermis development positive regulation of transcription, DNA-dependent striatin, NM_014574.1 cell cycle protein binding membrane calmodulin STRN3 fraction binding protein 3 calmodulin binding nucleus calmodulin binding cytoplasm cytosol membrane EF-hand BC005357.1 calcium ion binding calcium EFCAB2 binding domain 2 ubiquitin NM_005154.1/ DNA double-stranded DNA specific DEF topological binding peptidase 8 USP8 change ubiquitin- cysteine-type dependent endopeptidase activity protein catabolic process ubiquitin cycle ubiquitin thiolesterase activity cell proliferation ubiquitin-specific protease activity protein binding protein binding peptidase activity cysteine-type peptidase activity hydrolase activity golgi BC000284.1/ protein complex protein binding intracellular associated, DEF assembly gamma adaptin GGA2 transport protein binding endosome ear containing, intracellular protein transporter Golgi apparatus ARF binding protein transport activity protein 2 intracellular ADP-ribosylation trans-Golgi protein transport factor binding network protein transport endosome membrane vesicle- membrane mediated transport membrane coat clathrin adaptor complex sodium NM_001037.1/ transport ion channel activity membrane channel, DEF fraction voltage-gated, SCN1B ion transport voltage-gated ion membrane type I, beta channel activity sodium ion voltage-gated sodium integral to transport channel activity membrane sodium ion sodium channel transport activity synaptic sodium ion binding transmission PHD finger BF430956 transcription protein binding protein 3 PHF3 multicellular zinc ion binding organismal development metal ion binding IQ motif A1679073 signal GTPase inhibitor intracellular G13_Signaling_Pathway containing IQGAP1 transduction activity GTPase signal GTPase activator cytoplasm activating transduction activity protein 1 small GTPase GTPase activator actin filament mediated signal activity transduction regulation of Ras GTPase activator plasma small GTPase activity membrane mediated signal transduction protein binding membrane protein binding protein binding calmodulin binding calmodulin binding serine NM_013233.1 protein amino nucleotide binding membrane threonine STK39 acid fraction kinase 39 phosphorylation (STE20/SPS1 protein amino protein kinase activity nucleus homolog, acid yeast) phosphorylation response to protein nucleus stress serine/threonine kinase activity receptor signaling cytoplasm protein serine/threonine kinase activity protein-tyrosine kinase cytoplasm activity protein binding basolateral plasma membrane ATP binding apical plasma membrane ATP binding kinase activity transferase activity DCN1, AW468880 defective in DOUN1D1 cullin neddylation 1, domain containing I (S. cerevisiae) protein kinase, NM_005399.1/ fatty acid protein binding cAMP- Fatty_Acid_Synthesis AMP-activated, (DEF biosynthetic dependent beta 2 non- PRKAB2 process protein kinase catalytic complex subunit signal kinase activity AMP-activated transduction protein kinase complex lipid protein kinase binding biosynthetic process histidine triad AW418666 catalytic activity nucleotide HINT3 binding protein 3 TIP41, TOR NM_152902.1 protein binding signaling TIPRL pathway regulator-like (S. cerevisiae) serine/threonine/ AI492892 protein amino phosphoprotein tyrosine LOC730432 acid phosphatase activity interacting dephosphorylation protein similar to AI492892 dephosphorylation protein serine/threonine/ STYX tyrosine/serine/threonine tyrosine phosphatase interacting activity protein hydrolase activity phosphoric monoester hydrolase activity baculoviral IAP AI017106 ubiquitin cycle ubiquitin-protein intracellular repeat- BIRC6 ligase activity containing 6 apoptosis endopeptidase membrane (apollon) inhibitor activity fraction anti-apoptosis cysteine protease inhibitor activity anti-apoptosis ligase activity positive small conjugating regulation of protein ligase activity cell proliferation post- translational protein modification regulation of protein metabolic process protein tyrosine AI813654 protein binding phosphatase- PTPLB like (proline instead of catalytic arginine), member b bone AI457436 skeletal nucleotide binding integral to morphogenetic BMPR2 development plasma protein membrane receptor, type protein amino magnesium ion membrane II acid binding (serine/threonine phosphorylation kinase) transmembrane protein kinase activity integral to receptor protein membrane serine/threonine kinase signaling pathway transmembrane protein receptor protein serine/threonine kinase serine/threonine activity kinase signaling pathway regulation of transmembrane cell proliferation receptor protein serine/threonine kinase activity receptor signaling protein serine/threonine kinase activity receptor activity transforming growth factor beta receptor activity protein binding protein binding ATP binding kinase activity transferase activity manganese ion binding metal ion binding zinc finger and transcription nucleic acid binding intracellular BTB domain BF111616 regulation of DNA binding nucleus containing 2 ZBTB2 transcription, DNA-dependent protein binding zinc ion binding metal ion binding KIAA1333 AI823905 protein ubiquitin-protein intracellular KIAA1333 modification ligase activity process ubiquitin cycle protein binding nucleus protein binding cytoplasm zinc ion binding ligase activity metal ion binding kelch repeat BF000166 protein binding and BTB KBTBD2 (POZ) domain containing 2 forkhead box NM_001452.1 transcription DNA binding nucleus F2 FOXF2 regulation of DNA binding nucleus transcription, DNA-dependent transcription transcription factor nucleus from RNA activity polymerase II promoter extracellular transcription factor transcription matrix activity factor complex organization and biogenesis establishment of RNA polymerase II polarity of transcription factor embryonic activity epithelium negative transcription regulation of coactivator activity transcription, DNA-dependent positive transcription activator regulation of activity transcription, DNA-dependent embryonic gut sequence-specific development DNA binding sequence-specific DNA binding G patch NM_022078.1/ nucleic acid binding intracellular domain DEF containing 3 GPATCH3 SH2B adaptor NM_020979.1/ B-1 B cell signal transducer stress fiber protein 2 DEF homeostasis activity SH2B2 signal transmembrane ruffle transduction receptor protein tyrosine kinase adaptor protein activity intracellular SH3/SH2 adaptor cytoplasm signaling activity cascade intracellular SH3/SH2 adaptor cytoplasm signaling activity cascade insulin receptor protein binding actin filament signaling pathway cytokine and JAK pathway signal plasma chemokine transduction adaptor membrane mediated activity signaling pathway regulation of plasma metabolic membrane process actin membrane cytoskeleton organization and biogenesis regulation of immune response antigen receptor- mediated signaling pathway non-SMC NM_022346.1/ cell cycle binding nucleus condensin I DEF mitosis protein binding nucleus complex, NCAPG mitotic cytoplasm subunit G chromosome condensation mitotic chromosome condensation cell division sel-1 AI927770 Notch signaling binding endoplasmic suppressor of SEL1L pathway reticulum lin-12-like (C. elegans) endoplasmic reticulum membrane membrane integral to membrane integral to membrane casein kinase 1, BG534245 protein amino nucleotide binding cytoplasm alpha 1 CSNK1A1 acid phosphorylation protein amino protein acid serine/threonine kinase phosphorylation activity Wnt receptor casein kinase I activity signaling pathway ATP binding transferase activity myeloid/lymphoid AI394529 in utero DNA binding nucleus or mixed- MLL2 embryonic lineage development leukemia 2 transcription DNA binding nucleus regulation of protein binding histone transcription, methyltransferase DNA-dependent complex regulation of protein binding transcription, DNA-dependent zinc ion binding metal ion binding hypothetical AL137364.1 protein MGC24039 MGC24039 CDNA T86629 - FLJ30652 fis, clone DFNES2000011 CDNA BU689502 - FLJ33255 fis, clone ASTRO2005553 Importin 7 BG291787 protein import small GTPase soluble fraction 1PO7 into nucleus, regulator activity docking transport transporter activity nucleus intracellular binding nuclear pore protein transport signal protein binding nuclear pore transduction protein transport protein binding cytoplasm Ran GTPase binding protein transporter activity histone binding CDNA AA147933 - FLJ31066 fis, clone HSYRA2001153 Cri-du-chat AF056433 - region mRNA, clone NIBB11 AF088033 - ubiquitin cycle ubiquitin-specific cytoplasm protease activity ubiquitin cycle ubiquitin-specific endoplasmic protease activity reticulum peptidase activity Golgi apparatus cysteine-type peptidase activity hydrolase activity CDNA AI816281 - FLJ42233 fis, clone THYMU3000420 Thrombospondin 1 AW956580 cell motility endopeptidase extracellular Inflammatory_Response_Pathway THBS1 inhibitor activity region cell adhesion signal transducer extracellular TGF_Beta_Signaling_Pathway activity region multicellular structural molecule organismal activity development nervous system calcium ion binding development blood protein binding coagulation heparin binding hypothetical AA639752 protein LOC144871 LOC144871 vacuolar AW963328 transport binding protein sorting VPS41 intracellular protein binding 41 homolog (S. cerevisiae) protein transport protein transport zinc ion binding vesicle- metal ion binding mediated transport Transcribed BF433071 - locus, moderately similar to XP_222679.3 PREDlCTED: similar to FRBZ1 protein (FRBZI) [Rattus norvegicus] ESTs AW611729 unknown Moderately similar to unknown ALU_HUMAN ALU subfamily ESTs AW182938 unknown unknown

The foregoing demonstrates that PKC-activation elicits different genomic profiles in AD cells, as compared with control cells, which can be used to diagnose AD and individuals at risk for developing AD.

Patents, patent applications, publications, product descriptions, and protocols are cited throughout this application, the disclosures of which are incorporated herein by reference in their entireties for all purposes. 

1. A method of diagnosing Alzheimer's disease, said method comprising the steps of: i) contacting a population of test cells obtained from a subject suspected of having Alzheimer's disease with an agent that is a protein kinase C activator; and ii) detecting changes in expression of one or more genes in the test cells when compared to the expression of the same one or more genes in cells from control cells obtained from an individual without Alzheimer's disease, wherein a change in gene expression in the test cells compared to gene expression in the control cells indicates that the individual has Alzheimer's disease.
 2. The method of claim 1, wherein the protein kinase C activator is selected from the group consisting of bradykinin, bryostatin, bombesin, cholecystokinin, thrombin, prostaglandin F2-alpha or vasopressin.
 3. The method of claim 1, wherein the test cells are peripheral cells.
 4. The method of claim 3, wherein the test cells are selected from the group consisting of skin cells, blood cells, buccal mucosal cells, or cells from cerebrospinal fluid.
 5. The method of claim 3, wherein the test cells are fibroblast cells or epithelial cells.
 6. The method of claim 1, wherein the change in gene expression detected in the test cells compared with the control cells is an increase in gene expression.
 7. The method of claim 6, wherein the gene is selected from the group consisting of C14orf43 (lipopolysaccharide specific response protein-68; AV740879), PHF3 (PHD finger protein 3; BF430956), STRN3 (striatin-binding protein 3; NM_(—)014574.1), STK39 (serine threonine kinase 39, SPAK, NM_(—)013233); IPO7 (Ran binding protein 7; importin 7, BG291787); HLTF (helicase-like transcription factor; AI760760); EIF4G3 (Eukaryotic translation initiation factor 4, gamma 3; NM_(—)003760.2); NCAPG (Non-SMC condensing 1 complex, subunit-G; NM_(—)022346.1), TGFBR2 (TGF-β Receptor Type II; D50683.1); USP8 (Ubiquitin specific peptidase-8, NM_(—)005154.1); BAT2D1 (BAT2 domain containing 1 helicase-like transcription factor; AW238632); LOC144871 (hypothetical protein LOC144871, AA639752); homo sapiens full length insert cDNA clone (ubiquitin cycle protein, AF088033); RP11-345P4.4 (similar to solute carrier family 35, member E2, AL031282); THBS1 (Thrombospondin 1, AW956580); MLL2 (myeloid/lymphoid or mixed-lineage leukemia 2; AI394529); MGC24039 (hypothetical protein MGC24039, AL137364.1); FOXF2 (forkhead box F2, NM_(—)001452.1); ZBTB2 (zinc finger and BTB domain containing 2, BF111616); BMPR2 (bone morphogenetic protein receptor, type II, AI457436); Cri-du-chat region mRNA (clone NIBB11, AF056433); BIRC6 (baculoviral IAP repeat-containing 6, apollon, AI017106); SEL1L (sel-1 suppressor of lin-12-like, AI927770); cDNA FLJ42233 fis, clone THYMU3000420 (AI816281); ARID4B (AT rich interactive domain 4B (RBP1-like), NM_(—)016374); VPS41 (vacuolar protein sorting 41 homolog, AW963328); cDNA FLJ31066 fis, clone HSYRA2001153 (AA147933); EFCAB2 (EF-hand calcium binding domain 2, BC005357.1); CSNK1A1 (casein kinase 1, alpha 1, BG534245); cDNA FLJ33255 fis, clone ASTRO2005553 (BU689502); KIAA1333 (ubiquitin cycle protein, AI823905); ECT2 (epithelial cell transforming sequence 2 oncogene; NM_(—)018098.1); TFDP1 (transcription factor Dp-1, R60866); EST (AW611729); and EST (AW182938), homologs thereof, and combinations thereof.
 8. The method of claim 1, wherein the change in gene expression detected in the test cells compared with the control cells is a decrease in gene expression.
 9. The method of claim 8, wherein the gene is selected from the group consisting of SH2B2 (SH2B adaptor protein 2, NM_(—)020979); GGA2 (golgi associated, gamma adaptin ear containing, ARF binding protein 2, BC000284.1); SCN1B (sodium channel, voltage-gated, type I, beta, NM_(—)001037.1); PSPH (phosphoserine phosphatase, NM_(—)003832.1); GPATCH3 (G patch domain containing 3, NM_(—)022078.1); LOC730432 (serine/threonine/tyrosine interacting protein, AI492892); cDNA FLJ30652 fis, clone DFNES2000011 (T86629); HINT3 (histidine triad nucleotide binding protein 3, AW418666); DCUN1D1 (DCN1, defective in cullin neddylation 1, domain containing 1, AW468880); PRKAB2 (protein kinase, AMP-activated, beta 2 non-catalytic subunit, NM_(—)005399.1); transcribed locus (similar to FRBZ1 protein (FRBZ1), BF433071); TIPRL (TIP41, TOR signaling pathway regulator-like, NM_(—)152902.1); IQGAP1 (IQ motif containing GTPase activating protein 1, AI679073); PRRX1 (paired related homeobox 1, NM_(—)006902.2); KBTBD2 (kelch repeat and BTB (POZ) domain containing 2, BF000166); ATP2B4 (ATPase, calcium transporting, plasma membrane 4, NM_(—)001684.1); PTPLB (protein tyrosine phosphatase-like (proline instead of catalytic arginine), member b, AI813654), STYX (similar to serine/threonine/tyrosine interacting protein, AI492892), homologs thereof, and combinations thereof.
 10. The method of claim 1, wherein the change in gene expression detected in the test cells compared with the control cells is both an increase and decrease in gene expression.
 11. The method of claim 10, wherein the genes demonstrating increased expression are selected from the group consisting of C14orf43 (lipopolysaccharide specific response protein-68; AV740879), PHF3 (PHD finger protein 3; BF430956), STRN3 (striatin-binding protein 3; NM_(—)014574.1), STK39 (serine threonine kinase 39, SPAK, NM_(—)013233); IPO7 (Ran binding protein 7; importin 7, BG291787); HLTF (helicase-like transcription factor; A1760760); EIF4G3 (Eukaryotic translation initiation factor 4, gamma 3; NM_(—)003760.2); NCAPG (Non-SMC condensing 1 complex, subunit-G; NM_(—)022346.1), TGFBR2 (TGF-β Receptor Type II; D50683.1); USP8 (Ubiquitin specific peptidase-8, NM_(—)005154.1); BAT2D1 (BAT2 domain containing 1 helicase-like transcription factor; AW238632); LOC144871 (hypothetical protein LOC144871, AA639752); homo sapiens full length insert cDNA clone (ubiquitin cycle protein, AF088033); RP11-345P4.4 (similar to solute carrier family 35, member E2, AL031282); THBS1 (Thrombospondin 1, AW956580); MLL2 (myeloid/lymphoid or mixed-lineage leukemia 2; AI394529); MGC24039 (hypothetical protein MGC24039, AL137364.1); FOXF2 (forkhead box F2, NM_(—)001452.1); ZBTB2 (zinc finger and BTB domain containing 2, BF111616); BMPR2 (bone morphogenetic protein receptor, type II, AI457436); Cri-du-chat region mRNA (clone NIBB11, AF056433); BIRC6 (baculoviral IAP repeat-containing 6, apollon, AI017106); SEL1L (sel-1 suppressor of lin-12-like, AI927770); cDNA FLJ42233 fis, clone THYMU3000420 (AI816281); ARID4B (AT rich interactive domain 4B (RBP1-like), NM_(—)016374); VPS41 (vacuolar protein sorting 41 homolog, AW963328); cDNA FLJ31066 fis, clone HSYRA2001153 (AA147933); EFCAB2 (EF-hand calcium binding domain 2, BC005357.1); CSNK1A1 (casein kinase 1, alpha 1, BG534245); cDNA FLJ33255 fis, clone ASTRO2005553 (BU689502); KIAA1333 (ubiquitin cycle protein, AI823905); ECT2 (epithelial cell transforming sequence 2 oncogene; NM_(—)018098.1); and wherein the genes demonstrating decreased expression are selected from the group consisting of SH2B2 (SH2B adaptor protein 2, NM_(—)020979); GGA2 (golgi associated, gamma adaptin ear containing, ARF binding protein 2, BC000284.1); SCN1B (sodium channel, voltage-gated, type I, beta, NM_(—)001037.1); PSPH (phosphoserine phosphatase, NM_(—)003832.1); GPATCH3 (G patch domain containing 3, NM_(—)022078.1); LOC730432 (serine/threonine/tyrosine interacting protein, AI492892); cDNA FLJ30652 fis, clone DFNES2000011 (T86629); HINT3 (histidine triad nucleotide binding protein 3, AW418666); DCUN1D1 (DCN1, defective in cullin neddylation 1, domain containing 1, AW468880); PRKAB2 (protein kinase, AMP-activated, beta 2 non-catalytic subunit, NM_(—)005399.1); transcribed locus (similar to FRBZ1 protein (FRBZ1), BF433071); TIPRL (TIP41, TOR signaling pathway regulator-like, NM_(—)152902.1); IQGAP1 (IQ motif containing GTPase activating protein 1, AI679073); PRRX1 (paired related homeobox 1, NM_(—)006902.2); KBTBD2 (kelch repeat and BTB (POZ) domain containing 2, BF000166); ATP2B4 (ATPase, calcium transporting, plasma membrane 4, NM_(—)001684.1); PTPLB (protein tyrosine phosphatase-like (proline instead of catalytic arginine), member b, AI813654), homologs thereof, and combinations thereof.
 12. The method of claim 1, wherein the change in gene expression is measured using a microarray.
 13. The method of claim 12, wherein the microarray is a cell array comprising the test cell and the control cells.
 14. The method of claim 13 wherein the microarray is nucleic acid array wherein the nucleic acids are derived from the test and control cells.
 15. The method of claim 14, wherein the nucleic acid is cDNA.
 16. The method of claim 1, wherein the change in gene expression is measured using polymerase chain reaction.
 17. The method of claim 16, wherein the polymerase chain reaction is real-time polymerase chain reaction.
 18. The method of claim 1, wherein the Alzheimer's disease is sporadic Alzheimer's disease.
 19. The method of claim 1, wherein the Alzheimer's disease is early-stage Alzheimer's disease.
 20. The method of claim 1, wherein the Alzheimer's disease is young-onset Alzheimer's disease. 